Heat exchanger for vehicle

ABSTRACT

A heat exchanger for a vehicle may include a heat radiating portion provided with first and second connecting lines formed alternately by stacking plates, and receiving first and second operating fluids into the first and second connecting lines, a bifurcating portion connecting an inflow hole for flowing one operating fluid of the first and second operating fluids with an exhaust hole for exhausting the one operating fluid, and adapted for the one operating fluid to bypass the heat radiating portion according to a temperature of the one operating fluid, and a valve unit mounted corresponding to the inflow hole and adapted to flow the one operating fluid selectively to the heat radiating portion or the bifurcating portion according to the temperature of the one operating fluid flowing in the inflow hole.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No.10-2011-0072025 and No. 10-2011-0038972 filed in the Korean IntellectualProperty Office respectively on Jul. 20, 2011 and Apr. 26, 2011, theentire contents of which is incorporated herein for all purposes by thisreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heat exchanger for a vehicle. Moreparticularly, the present invention relates to a heat exchanger for avehicle which can control temperatures of at least two operating fluidsflowing into the heat exchanger.

2. Description of Related Art

Generally, a heat exchanger transfers heat from high-temperature fluidto low-temperature fluid through a heat transfer surface, and is used ina heater, a cooler, an evaporator, and a condenser.

Such a heat exchanger reuses heat energy or controls a temperature of anoperating fluid flowing therein for demanded performance. The heatexchanger is applied to an air conditioning system or a transmission oilcooler of a vehicle, and is mounted at an engine compartment.

Since the heat exchanger is hard to be mounted at the engine compartmentwith restricted space, studies for the heat exchanger with smaller size,lighter weight, and higher efficiency have been developed.

A conventional heat exchanger controls the temperatures of the operatingfluids according to a condition of a vehicle and supplies the operatingfluids to an engine, a transmission, or an air conditioning system. Forthis purpose, bifurcation circuits and valves are mounted on eachhydraulic line through which the operating fluids operated as heatingmedium or cooling medium passes. Therefore, constituent elements andassembling processes increase and layout is complicated.

If additional bifurcation circuits and valves are not used, heatexchanging efficiency cannot be controlled according to flow amount ofthe operating fluid. Therefore, the temperature of the operating fluidcannot be controlled efficiently.

The information disclosed in this Background of the Invention section isonly for enhancement of understanding of the general background of theinvention and should not be taken as an acknowledgement or any form ofsuggestion that this information forms the prior art already known to aperson skilled in the art.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing aheat exchanger for a vehicle having advantages of simultaneously warmingup and cooling operating fluids according to temperatures of theoperating fluids at a running state or an initial starting condition ofthe vehicle when the operating fluids are heat exchanged with each otherin the heat exchanger.

Various aspects of the present invention are directed to providing aheat exchanger for a vehicle having further advantages of improving fueleconomy and heating performance by controlling the temperatures of theoperating fluids according to a condition of the vehicle.

A heat exchanger for a vehicle according to one or more exemplaryembodiments of the present invention may include a heat radiatingportion provided with first and second connecting lines formedalternately by stacking a plurality of plates, and receiving first andsecond operating fluids into the first and second connecting lines, thefirst and second operating fluids heat-exchanging with each other duringpassing through the first and second connecting lines, a bifurcatingportion connecting an inflow hole for flowing one operating fluid of thefirst and second operating fluids with an exhaust hole for exhaustingthe one operating fluid, and adapted for the one operating fluid tobypass the heat radiating portion according to a temperature of the oneoperating fluid, and a valve unit mounted corresponding to the inflowhole and adapted to flow the one operating fluid selectively to the heatradiating portion or the bifurcating portion according to thetemperature of the one operating fluid flowing in the inflow hole.

In one or more exemplary embodiments, the first operating fluid flowsinto the heat radiating portion through a first inflow hole and flowsout from the heat radiating portion through a first exhaust hole, andthe first inflow hole is connected to the first exhaust hole through thefirst connecting line.

In one or more exemplary embodiments, the second operating fluid flowsinto the heat radiating portion through a second inflow hole and flowsout from the heat radiating portion through a second exhaust hole, andthe second inflow hole is connected to the second exhaust hole throughthe second connecting line.

In one or more exemplary embodiments, the first and second inflow holesare formed at both sides of a surface of the heat radiating portionalong a length direction, and the first and second exhaust holes aredistanced from the first and second inflow holes and are formed at theboth sides of the surface of the heat radiating portion along the lengthdirection.

In one or more exemplary embodiments, the bifurcating portion connectsthe first inflow hole with the first exhaust hole, and is protruded froma surface of the heat radiating portion.

In one or more exemplary embodiments, the first inflow hole and thefirst exhaust hole are formed at corner portions of the surface of theheat radiating portion facing diagonally with each other.

In one or more exemplary embodiments, the second inflow hole and thesecond exhaust hole are formed at corner portions of the surface of theheat radiating portion at which the first inflow hole and the firstexhaust hole are not positioned and which face diagonally with eachother.

In one or more exemplary embodiments, the first operating fluid is acoolant coming from a radiator and the second operating fluid is atransmission oil coming from an automatic transmission.

In one or more exemplary embodiments, the coolant circulates through thefirst inflow hole, the first connecting line, and the first exhausthole, and the transmission oil circulates through the second inflowhole, the second connecting line, and the second exhaust hole.

In one or more exemplary embodiments, the bifurcating portion isprovided with a bypass line adapted to flow the coolant flowing in thebifurcating portion through the first inflow hole to the first exhausthole directly.

In one or more exemplary embodiments, the valve unit may include amounting cap fixedly mounted at the other end of the heat radiatingportion corresponding to the first inflow hole, and a deformable memberinserted in the mounting cap and adapted to extend or contract accordingto the temperature of the operating fluid.

In one or more exemplary embodiments, the deformable member is made fromshape memory alloy adapted to extend or contract according to thetemperature of operating fluid.

In one or more exemplary embodiments, the deformable member may includea pair of fixed portions positioned at both sides thereof in a lengthdirection and adapted not to being deformed according to thetemperature, and a deformable portion disposed between the pair of fixedportions and adapted to extend or contract according to the temperatureof the operating fluid.

In one or more exemplary embodiments, the deformable member is formed byoverlapping and contacting a plurality of ring members with each otherin a coil spring shape.

In one or more exemplary embodiments, the mounting cap may include amounting portion fixedly mounted at the heat radiating portion, and aguide portion extending from the mounting portion toward the firstinflow hole and adapted to guide the deformable member in a case thatthe deformable member inserted therein is deformed.

In one or more exemplary embodiments, a screw is formed at an exteriorcircumference of the mounting portion so as to be threaded to the heatradiating portion.

In one or more exemplary embodiments, at least one of through-holes isformed at an exterior circumference of the guide portion.

In one or more exemplary embodiments, the heat exchanger may furtherinclude a sealing for preventing the operating fluid passing through theheat radiating portion from leaking to the exterior, wherein the sealingis mounted between the mounting portion and the guide portion.

In one or more exemplary embodiments, the heat radiating portionheat-exchanges the first and second operating fluids by counterflow ofthe first and second operating fluids.

In one or more exemplary embodiments, the heat radiating portion is aheat radiating portion of plate type where a plurality of plates isstacked.

A heat exchanger for a vehicle according to another aspect of thepresent invention may include a heat radiating portion provided withfirst and second connecting lines formed alternately by stacking aplurality of plates, and receiving first and second operating fluidsinto the first and second connecting lines, the first and secondoperating fluids heat-exchanging with each other during passing throughthe first and second connecting lines, and a bifurcating portionconnecting an inflow hole for flowing one operating fluid of the firstand second operating fluids with an exhaust hole for exhausting the oneoperating fluid, and adapted for the one operating fluid to bypass theheat radiating portion according to a flow amount of the one operatingfluid.

In one or more exemplary embodiments, the first operating fluid flowsinto the heat radiating portion through a first inflow hole and flowsout from the heat radiating portion through a first exhaust hole, andthe first inflow hole is connected to the first exhaust hole through thefirst connecting line.

In one or more exemplary embodiments, the second operating fluid flowsinto the heat radiating portion through a second inflow hole and flowsout from the heat radiating portion through a second exhaust hole, andthe second inflow hole is connected to the second exhaust hole throughthe second connecting line.

In one or more exemplary embodiments, the first and second inflow holesare formed at both sides of a surface of the heat radiating portionalong a length direction. In addition, the first and second exhaustholes are distanced from the first and second inflow holes and areformed at the both sides of the surface of the heat radiating portionalong the length direction.

In one or more exemplary embodiments, the bifurcating portion connectsthe first inflow hole with the first exhaust hole, and is protruded froma surface of the heat radiating portion.

In one or more exemplary embodiments, the first operating fluid is acoolant coming from a radiator and the second operating fluid is atransmission oil coming from an automatic transmission.

In one or more exemplary embodiments, the coolant circulates through thefirst inflow hole, the first connecting line, and the first exhausthole, and the transmission oil circulates through the second inflowhole, the second connecting line, and the second exhaust hole.

In one or more exemplary embodiments, the bifurcating portion isprovided with a bypass line adapted to flow the coolant flowing in thebifurcating portion through the first inflow hole to the first exhausthole directly.

In one or more exemplary embodiments, the heat radiating portionheat-exchanges the first and second operating fluids by counterflow ofthe first and second operating fluids.

The methods and apparatuses of the present invention have other featuresand advantages which will be apparent from or are set forth in moredetail in the accompanying drawings, which are incorporated herein, andthe following Detailed Description, which together serve to explaincertain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a cooling system of an automatictransmission to which a heat exchanger for a vehicle according to anexemplary embodiment of the present invention is applied.

FIG. 2 is a perspective view of a heat exchanger for a vehicle accordingto an exemplary embodiment of the present invention.

FIG. 3 is a partially cut-away perspective view of a heat exchanger fora vehicle according to an exemplary embodiment of the present invention.

FIG. 4 is a cross-sectional view taken along the line A-A in FIG. 2.

FIG. 5 is a cross-sectional view taken along the line B-B in FIG. 2.

FIG. 6 is a perspective view of a valve unit used in a heat exchangerfor a vehicle according to an exemplary embodiment of the presentinvention.

FIG. 7 is an exploded perspective view of a valve unit according to anexemplary embodiment of the present invention.

FIG. 8 is a perspective view of a valve unit at an extended stateaccording to an exemplary embodiment of the present invention.

FIG. 9 to FIG. 10 are perspective and cross-sectional views fordescribing operation of a heat exchanger for a vehicle according to anexemplary embodiment of the present invention.

FIG. 11 is a perspective view of a heat exchanger for a vehicleaccording to another exemplary embodiment of the present invention.

FIG. 12 is a cross-sectional view taken along the line C-C in FIG. 11.

FIG. 13 is a cross-sectional view taken along the line D-D in FIG. 11.

FIG. 14 is a partially cut-away perspective view of a heat exchanger fora vehicle according to another exemplary embodiment of the presentinvention.

It should be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variousfeatures illustrative of the basic principles of the invention. Thespecific design features of the present invention as disclosed herein,including, for example, specific dimensions, orientations, locations,and shapes will be determined in part by the particular intendedapplication and use environment.

In the figures, reference numbers refer to the same or equivalent partsof the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of thepresent invention(s), examples of which are illustrated in theaccompanying drawings and described below. While the invention(s) willbe described in conjunction with exemplary embodiments, it will beunderstood that the present description is not intended to limit theinvention(s) to those exemplary embodiments. On the contrary, theinvention(s) is/are intended to cover not only the exemplaryembodiments, but also various alternatives, modifications, equivalentsand other embodiments, which may be included within the spirit and scopeof the invention as defined by the appended claims.

An exemplary embodiment of the present invention will hereinafter bedescribed in detail with reference to the accompanying drawings.

Exemplary embodiments described in this specification and drawings arejust exemplary embodiments of the present invention. It is to beunderstood that there can be various modifications and equivalentsincluded in the spirit of the present invention at the filing of thisapplication.

FIG. 1 is a schematic diagram of a cooling system of an automatictransmission to which a heat exchanger for a vehicle according to anexemplary embodiment of the present invention is applied, FIG. 2 is aperspective view of a heat exchanger for a vehicle according to anexemplary embodiment of the present invention, FIG. 3 is a partiallycut-away perspective view of a heat exchanger for a vehicle according toan exemplary embodiment of the present invention, FIG. 4 is across-sectional view taken along the line A-A in FIG. 2, FIG. 5 is across-sectional view taken along the line B-B in FIG. 2, FIG. 6 is aperspective view of a valve unit used in a heat exchanger for a vehicleaccording to an exemplary embodiment of the present invention, and FIG.7 is an exploded perspective view of a valve unit according to anexemplary embodiment of the present invention.

Referring to the drawings, a heat exchanger 100 for a vehicle accordingto an exemplary embodiment of the present invention applies to a coolingsystem of an automatic transmission for a vehicle.

The cooling system of the automatic transmission, as shown in FIG. 1, isprovided with a cooling line C.L for cooling an engine. A coolant passesthrough the radiator 20 having a cooling fan 21 through a water pump 10and is cooled by the radiator 20. A heater core 30 connected to aheating system of the vehicle is mounted at the cooling line C.L.

A heat exchanger 100 for a vehicle according to an exemplary embodimentof the present invention warms up or cools operating fluids according totemperatures of the operating fluids flowing in at a running state or aninitial starting condition of the vehicle when the temperatures of theoperating fluids are controlled in the heat exchanger 100 through heatexchange.

For this purpose, the heat exchanger 100 for a vehicle according to anexemplary embodiment of the present invention is disposed between thewater pump 10 and the heater core 30, and is connected to an automatictransmission 40 through an oil line O.L.

That is, the operating fluids includes a coolant flowing from theradiator 20 and a transmission oil flowing from the automatictransmission 40 according to the present exemplary embodiment. Thecoolant and the transmission oil are heat exchanged with each other inthe heat exchanger 100 such that a temperature of the transmission oilis controlled.

The heat exchanger 100, as shown in FIG. 2 and FIG. 3, includes a heatradiating portion 110, a bifurcating portion 120, and a valve unit 130,and the heat radiating portion 110, the bifurcating portion 120, and thevalve unit 130 will be described in detail.

The heat radiating portion 110 is formed by stacking a plurality ofplates 112, and a plurality of connecting lines 114 is formed betweenthe neighboring plates 112. In addition, the coolant flows through oneof the neighboring connecting lines 114, and the transmission oil flowsthrough the other of the neighboring connecting lines 114. At this time,heat is exchanged between the coolant and the transmission oil.

The heat radiating portion 110 exchanges heat between the coolant andthe transmission oil through counterflow of the coolant and thetransmission oil.

The heat radiating portion 110 is a heat radiating portion of plate type(or disk type) where the plurality of plates 112 is stacked.

In addition, the bifurcating portion 120 connects one of inflow holes116 for flowing the operating fluids into the heat radiating portion 110with one of exhaust holes 118 for discharging the operating fluids fromthe heat radiating portion 110, and is mounted at an exterior of theheat radiating portion 110. The bifurcating portion 120 is configuredfor the operating fluid to bypass the heat radiating portion 110 by thevalve unit 130 operated according to the temperature of the operatingfluid.

The inflow holes 116 includes first and second inflow holes 116 a and116 b formed at both sides of a surface of the heat radiating portion110 along a length direction according to the present exemplaryembodiment.

In addition, the exhaust holes 118 includes first and second exhaustholes 118 a and 118 b formed at the both sides of the surface of theheat radiating portion 110 along the length direction. The first andsecond exhaust holes 118 a and 118 b correspond to the first and secondinflow holes 116 a and 116 b and are distanced from the first and secondinflow holes 116 a and 116 b. The first and second exhaust holes 118 aand 118 b are connected respectively to the first and second inflowholes 116 a and 116 b through the respective connecting line 114 in theheat radiating portion 110.

The first inflow hole 116 a and the first exhaust hole 118 a are formedat corner portions of the surface of the heat radiating portion 110diagonally.

The second inflow hole 116 b and the second exhaust hole 118 b areformed at corner portions of the surface of the heat radiating portion110 diagonally, and confronts respectively with the first inflow hole116 a and the first exhaust hole 118 a.

The bifurcating portion 120 connects the first inflow hole 116 a withthe first exhaust hole 118 a, and is protruded from the surface of theheat radiating portion 110.

According to the present exemplary embodiment, the coolant circulatesthrough the first inflow hole 116 a and the first exhaust hole 118 a,and the transmission oil circulates through the second inflow hole 116 band the second exhaust hole 118 b.

Connecting ports are mounted respectively at the first inflow hole 116 aand the first exhaust hole 118 a, and are connected to the radiator 20through connecting hoses connected to the connecting ports. In addition,connecting ports are mounted respectively at the second inflow hole 116b and the second exhaust hole 118 b, and are connected to the automatictransmission 40 through connecting hoses connected to the connectingports.

The connecting line 114, as shown in FIG. 4 and FIG. 5, includes a firstconnecting line 114 a through which the coolant flows and a secondconnecting line 114 b through with the transmission oil passes accordingto the present exemplary embodiment. The first connecting line 114 a andthe second connecting line 114 b are formed alternately.

The bifurcating portion 120 includes a bypass line 122. The bypass line122 is adapted to exhaust the coolant flowing in the bifurcating portion120 through the first inflow hole 116 a to the first exhaust hole 118 adirectly.

In addition, the valve unit 130 is mounted at the heat radiating portion110 corresponding to the first inflow hole 116 a, and flows the coolantto the heat radiating portion 110 or to the bypass line 122 according tothe temperature of the coolant.

The valve unit 130, as shown in FIG. 6 and FIG. 7, includes a mountingcap 132 and a deformable member 138, and the mounting cap 132 and thedeformable member 138 will be described in detail.

The mounting cap 132 is fixedly mounted at the other surface of the heatradiating portion 110 corresponding to the first inflow hole 116 a.

The mounting cap 132 includes a mounting portion 134 fixedly mounted atthe heat radiating portion 110 and a guide portion 136 extending fromthe mounting portion 134 toward the first inflow hole 116 a. Thedeformable member 138 is inserted in the guide portion 136. The guideportion 136 guides the deformable member 138 when the deformable member138 extends or contracts.

A screw N is formed at an exterior circumference of the mounting portion134 such that the mounting portion 134 is threaded to an interiorcircumference of the heat radiating portion 110, and tab formingcorresponding to the screw N is performed at the interior circumferenceof the other surface of the heat radiating portion 110 corresponding tothe first inflow hole 116 a.

In addition, at least one of through-hole 137 is formed at an exteriorcircumference of the guide portion 136. The through-hole 137 isconfigured so that the coolant flowed in the extended deformable member138 flows to the first connecting line 114 a of the heat radiatingportion 110 smoothly.

According to the present exemplary embodiment, a sealing 146 is mountedat the mounting cap 132 so as to prevent the coolant from being leaked.The sealing 146 may be mounted between the mounting portion 134 and theguide portion 136.

That is, the sealing 146 seals a gap between the interior circumferenceof the heat radiating portion 110 and the exterior circumference of themounting portion 134 such that the operating fluid is prevented frombeing leaked to the exterior of the heat radiating portion 110 along thescrew N of the mounting portion 134 threaded to the heat radiatingportion 110.

In addition, the deformable member 138 is inserted in the guide portion136 of the mounting cap 132, and extends or contracts according to thetemperature of the coolant flowed into the first inflow hole 116 a.

The deformable member 138 can be made from shape memory alloy that canextend or contract according to the temperature of the operating fluid.

The shape memory alloy (SMA) is alloy that remembers a shape at apredetermined temperature. The shape of the shape memory alloy can bechanged at a different temperature from the predetermined temperature.If the shape memory alloy, however, is cooled or heated to thepredetermined temperature, the shape memory alloy returns to an originalshape.

The deformable member 138 made from the shape memory alloy materialincludes a pair of fixed portions 142 and a deformable portion 144, andthe fixed portion 142 and the deformable portion 144 will be describedin detail.

The pair of fixed portions 142 is positioned at both end portions of thedeformable member 138 in a length direction, and a shape of the fixedportion does not change according to the temperature. That is, ringmembers forming the fixed portion 142 are fixed with each other throughsuch as welding.

In addition, the deformable portion 144 is positioned between the fixedportion 142, and extends or contracts according to the temperature ofthe operating fluid. That is, ring members forming the deformableportion 144 is extendably or contractably connected to each other.

The deformable member 138 has a shape similar to that of a circular coilspring.

The deformable member 138 is inserted in the guide portion 136 of themounting cap 132 at a contracted state, and is deformed according to thetemperature of the operating fluid flowing in the deformable member 138through the first inflow hole 116 a so as to selectively open or closethe first connecting line 114 a.

That is, if he operating fluid having a higher temperature than thepredetermined temperature flows in the valve unit 130, the deformableportion 144 of the deformable member 138 extends, as shown in FIG. 8.

Accordingly, the ring members forming the deformable portion 144 of thedeformable member 138 are distanced from each other so as to form aspace S, and the operating fluid flows out through the space S.

At this time, the ring members forming the fixed portion 142 are fixedto each other, and the fixed portion 142 does not extend.

If the operating fluid having a lower temperature than the predeterminedtemperature flows into the first inflow hole 116 a, the deformableportion 144 contracts to an original shape shown in FIG. 6 and the spaceS is closed.

Operation and function of the heat exchanger 100 according to anexemplary embodiment of the present invention will be described indetail.

FIG. 9 to FIG. 10 are perspective and cross-sectional views fordescribing operation of a heat exchanger for a vehicle according to anexemplary embodiment of the present invention.

If the temperature of the coolant flowing through the first inflow hole116 a is lower than the predetermined temperature, the deformable member138 of the valve unit 130 does not deform and maintains an originalshape as shown in FIG. 9.

The coolant does not flow into the first connecting line 114 a of theheat radiating portion 110, but flows directly to the first exhaust hole118 a through the bypass line 122 formed in the bifurcating portion 120.

Accordingly, the transmission oil flowing into the heat radiatingportion 110 through the second inflow hole 116 b and passing through thesecond connecting line 114 b does not heat exchange with the coolant.

If the transmission oil should be warmed up according to a condition ora mode of the vehicle such as a running state, an idle mode, or aninitial starting, the bypass line 122 prevents the coolant of lowtemperature from flowing into the first connecting line 114 a.Therefore, it is prevented that the temperature of the transmission oilis lowered through heat exchange with the coolant.

If the temperature of the coolant, on the contrary, is higher than thepredetermined temperature; the deformable member 138 of the valve unit130 extends and the space S is formed between the ring members formingthe deformable portion 144 as shown in FIG. 10.

The coolant passing through the first inflow hole 116 a flows throughthe first connecting line 114 a. After that, the coolant is dischargedthrough the first exhaust hole 118 a.

Therefore, the coolant passes through the first connecting line 114 a ofthe heat radiating portion 110 and heat exchanges with the transmissionoil flowing in through the second inflow hole 116 b and passing throughthe second connecting line 114 b. Therefore, the temperatures of thecoolant and the transmission oil are controlled in the heat radiatingportion 110.

Since the first and second inflow holes 116 a and 116 b are formed atthe corner portions of the heat radiating portion 110 diagonally, thecoolant and the transmission oil flow to opposite directions and areheat exchanged. Therefore, heat exchange is performed more efficiently.

Therefore, the transmission oil is cooled through heat exchange with thecoolant in the heat radiating portion 110 and is then supplied to theautomatic transmission 40.

That is, since the heat exchanger 100 supplies the cooled transmissionoil to the automatic transmission 40 rotating at a high speed,occurrence of slip in the automatic transmission 40 is prevented.

If the heat exchanger 100 according to an exemplary embodiment of thepresent invention is applied, the operating fluids can be warmed up andcooled simultaneously by using the temperatures of the operating fluidsat the running state or the initial starting condition of the vehicle.Therefore, the temperatures of the operating fluids can be controlledefficiently.

Since the temperatures of the operating fluids can be controlledaccording to the condition of the vehicle, fuel economy and heatingperformance may be improved. In addition, assembling processes may bereduced due to a simple structure.

Since additional bifurcation circuits are not needed, production costmay be curtailed and workability may be improved.

If the operating fluid is the transmission oil in the automatictransmission 40, hydraulic friction at a cold starting may be lowereddue to fast warm up. In addition, slip may be prevented and durabilitymay be maintained at driving due to excellent cooling performance.Therefore, fuel economy and durability of the transmission may beimproved.

In addition, since the deformable member 138 is made from the shapememory alloy, structure of the valve unit 130 is very simple. Since thevalve unit 130 performs conversion of the hydraulic lines of theoperating fluid according to the temperature of the operating fluid,flow of the operating fluid can be controlled accurately. Therefore,constituent elements can be simplified and production cost may becurtailed. In addition, weight may be reduced.

Since responsiveness of the valve according to the temperature of theoperating fluid is improved, flow of the operating fluid may becontrolled efficiently.

It is exemplified in this specification that the coolant and thetransmission oil are used as the operating fluids, but the operatingfluids are not limited to these. All the operating fluids that requireswarming up or cooling can be used.

In addition, the heat exchanger according to an exemplary embodiment mayfurther include covers and brackets that prevent damage of the heatexchanger and other components or that are used for fixing the heatexchanger to other components or the engine compartment.

FIG. 11 is a perspective view of a heat exchanger for a vehicleaccording to another exemplary embodiment of the present invention, FIG.12 is a cross-sectional view taken along the line C-C in FIG. 11, FIG.13 is a cross-sectional view taken along the line D-D in FIG. 11, andFIG. 14 is a partially cut-away perspective view of a heat exchanger fora vehicle according to another exemplary embodiment of the presentinvention.

In another exemplary embodiment of the present invention, the operatingfluids includes the coolant flowing from the radiator 20 and thetransmission oil flowing from the automatic transmission 40 according tothe present exemplary embodiment. The coolant and the transmission oilare heat exchanged with each other in the heat exchanger 100 such that atemperature of the transmission oil is controlled.

The heat exchanger 100, as shown in FIG. 11 to FIG. 13, includes theheat radiating portion 210 and the bifurcating portion 220, and the heatradiating portion 210 and the bifurcating portion 220 will be describedin detail.

The heat radiating portion 210 is formed by stacking a plurality ofplates 211, and a plurality of connecting lines 213 is formed betweenthe neighboring plates 211. In addition, the coolant flows through oneof the neighboring connecting lines 213, and the transmission oil flowsthrough the other of the neighboring connecting lines 213. At this time,heat is exchanged between the coolant and the transmission oil.

The heat radiating portion 210 exchanges heat between the coolant andthe transmission oil through counterflow of the coolant and thetransmission oil.

The heat radiating portion 210 is a heat radiating portion of plate type(or disk type) where the plurality of plates 211 is stacked.

In addition, the bifurcating portion 220 connects one of inflow holes215 for flowing the operating fluids into the heat radiating portion 210with one of exhaust holes 217 for discharging the operating fluids fromthe heat radiating portion 210, and is mounted at an exterior of theheat radiating portion 210. The bifurcating portion 220 is configuredfor the operating fluid to bypass the heat radiating portion 210 withoutpassing through the connecting lines 213 according to a flow amount ofthe operating fluid.

The bifurcating portion 220 connects any one of the inflow holes 215with any one of the exhaust holes 217 in the heat radiating portion 210.That is, a portion of the inflow holes 215 is connected to a portion ofthe exhaust holes 217 through the connecting lines 213, and anotherportion of the inflow holes 215 is connected to another portion of theexhaust holes 217 through the connecting lines 213 and the bifurcatingportion 220.

The inflow holes 215 includes first and second inflow holes 215 a and215 b formed at both sides of the surface of the heat radiating portion210 along the length direction according to the present exemplaryembodiment.

In addition, the exhaust holes 217 includes first and second exhaustholes 217 a and 217 b formed at the both sides of the surface of theheat radiating portion 210 along the length direction. The first andsecond exhaust holes 217 a and 217 b correspond to the first and secondinflow holes 215 a and 215 b and are distanced from the first and secondinflow holes 215 a and 215 b. The first and second exhaust holes 217 aand 217 b are connected respectively to the first and second inflowholes 215 a and 215 b through the respective connecting line 213 in theheat radiating portion 210.

The first inflow hole 215 a and the first exhaust hole 217 a are formedat corner portions of the surface of the heat radiating portion 210diagonally.

The second inflow hole 215 b and the second exhaust hole 217 b areformed at corner portions of the surface of the heat radiating portion210 diagonally, and confronts respectively with the first inflow hole215 a and the first exhaust hole 217 a.

The bifurcating portion 220 connects the first inflow hole 215 a withthe first exhaust hole 217 a, and is protruded from the surface of theheat radiating portion 210.

According to the present exemplary embodiment, the coolant circulatesthrough the first inflow hole 215 a and the first exhaust hole 217 a,and the transmission oil circulates through the second inflow hole 215 band the second exhaust hole 217 b.

Connecting ports are mounted respectively at the first inflow hole 215 aand the first exhaust hole 217 a, and are connected to the radiator 20through connecting hoses connected to the connecting ports. In addition,connecting ports are mounted respectively at the second inflow hole 215b and the second exhaust hole 217 b, and are connected to the automatictransmission 40 through connecting hoses connected to the connectingports.

The connecting line includes a first connecting line 213 a through whichthe coolant flows and a second connecting line 213 b through with thetransmission oil passes according to the present exemplary embodiment.The first connecting line 213 a and the second connecting line 213 b areformed alternately.

The bifurcating portion 220 includes a bypass line 221. The bypass line221 is adapted to exhaust the coolant flowing in the bifurcating portion220 through the first inflow hole 215 a to the first exhaust hole 217 adirectly.

If the flow amount of the coolant flowing in through the first inflowhole 215 a is small, the bypass line 221 does not flow the coolant intothe first connecting line 213 a of the heat radiating portion 210 butexhausts the coolant directly into the first exhaust hole 217 a.

If the transmission oil should be warmed up according to the conditionor the mode of the vehicle such as the running state, the idle mode, orthe initial starting, the bypass line 221 prevents the coolant fromflowing into the first connecting line 213 a. Therefore, it is preventedthat the temperature of the transmission oil is lowered through heatexchange with the coolant.

If the flow amount of the coolant, on the contrary, is large, thecoolant flows into the first connecting line 213 a as well as the bypassline 221. At this time, the transmission oil is flowed into the secondconnecting line 213 b from the automatic transmission 40 through thesecond inflow hole 215 b. Therefore, the coolant passing through thefirst connecting line 213 a and the transmission oil passing through thesecond connecting line 213 b are heat exchanged with each other in theheat radiating portion 210.

Therefore, the transmission oil is cooled through heat exchange with thecoolant in the heat radiating portion 210 and is then supplied to theautomatic transmission 40.

That is, since the heat exchanger 100 supplies the cooled transmissionoil to the automatic transmission 40 rotating at a high speed,occurrence of slip in the automatic transmission 40 is prevented.

If the heat exchanger 100 according to another exemplary embodiment ofthe present invention is applied, the operating fluids can be warmed upand cooled simultaneously by using the flow amount of the operatingfluids at the running state or the initial starting condition of thevehicle. Therefore, the temperatures of the operating fluids can becontrolled efficiently.

For convenience in explanation and accurate definition in the appendedclaims, the terms “upper”, “lower”, “inner” and “outer” are used todescribe features of the exemplary embodiments with reference to thepositions of such features as displayed in the figures.

The foregoing descriptions of specific exemplary embodiments of thepresent invention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteachings. The exemplary embodiments were chosen and described in orderto explain certain principles of the invention and their practicalapplication, to thereby enable others skilled in the art to make andutilize various exemplary embodiments of the present invention, as wellas various alternatives and modifications thereof. It is intended thatthe scope of the invention be defined by the Claims appended hereto andtheir equivalents.

1-18. (canceled) 19: A heat exchanger for a vehicle, comprising: a heatradiating portion provided with first and second connecting lines formedalternately by stacking a plurality of plates, and receiving first andsecond operating fluids into the first and second connecting linesrespectively, the first and second operating fluids heat-exchanging witheach other during passing through the first and second connecting lines;and a bifurcating portion fluid-connecting an inflow hole for flowingone operating fluid of the first and second operating fluids with anexhaust hole for exhausting the one operating fluid, and adapted for theone operating fluid to bypass the heat radiating portion according to aflow amount of the one operating fluid. 20: The heat exchanger of claim19, wherein the first operating fluid flows into the heat radiatingportion through a first inflow hole and flows out from the heatradiating portion through a first exhaust hole, and the first inflowhole is connected to the first exhaust hole through the first connectingline, the second operating fluid flows into the heat radiating portionthrough a second inflow hole and flows out from the heat radiatingportion through a second exhaust hole, and the second inflow hole isconnected to the second exhaust hole through the second connecting line,the first and second inflow holes are formed at both sides of a surfaceof the heat radiating portion along a length direction, and the firstand second exhaust holes are distanced from the first and second inflowholes and are formed at the both sides of the surface of the heatradiating portion along the length direction. 21: The heat exchanger ofclaim 20, wherein the bifurcating portion connects the first inflow holewith the first exhaust hole, and is protruded from a surface of the heatradiating portion such that the bifurcating portion is positioned higherthan the heat radiating portion. 22: The heat exchanger of claim 20,wherein the first operating fluid is a coolant coming from a radiatorand the second operating fluid is a transmission oil coming from anautomatic transmission. 23: The heat exchanger of claim 22, wherein thecoolant circulates through the first inflow hole, the first connectingline, and the first exhaust hole, and the transmission oil circulatesthrough the second inflow hole, the second connecting line, and thesecond exhaust hole. 24: The heat exchanger of claim 23, wherein thebifurcating portion is provided with a bypass line bifurcated from thefirst inflow hole and adapted to flow the coolant flowing in thebifurcating portion through the first inflow hole to the first exhausthole directly. 25: The heat exchanger of claim 19, wherein the heatradiating portion heat-exchanges the first and second operating fluidsby counterflow of the first and second operating fluids.